• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.648-656
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• 2010

Global warming brings changes of natural ecosystems and affects on the plant growth response. Quercus acutissima and Q. variabilis are taxonomically similar and dominant native species in deciduous forests in South Korea. In order to understand the growth response of Q. acutissima and Q. variabilis to global warming condition, we cultivated the seedling of the two oak species in ambient condition(control) and treatment with elevated $CO_2$(700~800ppm) and increased air temperature(approximately $3^{\circ}C$ above than control). Then we measured the growth characteristic among them and analyzed the relationship between two species using PCA ordination. Stem length and total plant weight of Q. acutissima were significantly affected by elevated $CO_2$ concentration and increased air temperature. Stem diameter and weight of Q. variabilis were significantly affected by elevated $CO_2$ concentration and increased air temperature(p<0.05). The variation characteristics of Q. acutissima were changed more than Q. variabilis by elevated $CO_2$ concentration and increased air temperature. These result suggested that Q. acutissima was more sensitive to global warming situation than Q. variabilis in central region of Korea. PCA ordination showed that two species were arranged by two distinct groups based on 10 characters by elevated $CO_2$ and increased air temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.621-627
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• 2009

In order to standardize the juvenile abalone rearing technique, we selected sample farms by region in East, West and South coasts of Korea and Jeju island. We also have reviewed previous literature and visited farms to survey on the management of abalone juvenile production, spawning, hatching and so forth. Results of investigation are as follows: The light colors of tanks for larvae breeding are good for a frequent examination of larvae behaviour changes during the breeding period. The tank for the abalone juvenile production is a rectangular form in general and its size should amount to 3.5 m in length and 1.2 m width. It also should be built with proper drainage. The best age and size of adult for juvenile production are 3-6 years old individuals, with 9-12 cm separate burial and 125-150 g average weight. To induce spawning, the use of the exposure on air and ultraviolet ray together was the most effective. The density of larvae by plate should be 150-300 individuals and the proper stocking density was est imated and amount to 10-30 individuals. It has been shown that a correlation between water surface size($X_1$) and number of plates ($Y_1$), when producing abalone juveniles, is quite high and it is described by equation $Y_1=138.88X_1-5,736.8\;(R^2=0.9028)$. In addition, it has also been shown that a correlation between production of abalone juveniles ($Y_2$) and number of plates ($X_2$) is high and it is described by equation $Y_2=4.554X_2+12,493\;(R^2=0.8818)$. In Jindo region where a mass production of juveniles abalone has been done, it was shown, that a correlation between rearing water surface size ($X_3$) and production of juveniles abalone ($Y_3$) is very high and this relationship was described by the equation $Y_3=747.03X_2+94,359(R^2=0.9809)$. It has also been shown that a correlation between water surface size ($X_4$) and production of abalone juveniles ($Y_4$) in nationwide is high and the relationship between this variables was described by equation $Y_4=635.85X_4+99,923\;(R^2=0.9020)$.

• Journal of Life Science
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• v.17 no.8 s.88
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• pp.1104-1110
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• 2007

The number of investigated fish collected from the Andong and the Imha reservoir were 2,540 individuals 20 species belonging to 7 families, 850 individuals 11 species belonging to 4 families respectively from May 2005 to March 2006. The total number of the common 3 species individuals investigated caught from the Andong reservoir and the Imha reservoir were 486 individuals and 124 individuals respectively. The investigated individuals is similar(${\pm}2.5$ mm) to 171 individuals make a comparative study. The Opsariichthys uncirostris, Culter brevicauda, Hemiculter eigenmanni of length-weight relationship were TW = $0.00007TL^{3.0543}$, TW = $0.0000009TL^{3.3654}$, TW = $0.00000^{3.3872}$ in the Andong reservoir and TW = $0.00002TL^{2.8493}$, TW = $0.00001TL^{2.8744}$, TW = $0.000004TL^{3.1082}$ in the Imha reservoir respectively. The Condition factor(K) of the Andong reservoir showed the positive slopes in all three species and to be in a good nutrition condition; where as the condition factor(K) of the Imha reservoir showed the negative slopes in two species except in H. eigenmanni and appeared to be in a little bad nutrition condition. Relative condition factor(Kn) indicating that O. uncirostris and C. brevicauda in Andong reservoir is more rotund than ones of Imha reservoir but H. eigenmanni in the Imha reservoir is more rotund than the ones of the Andong reservoir.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.469-485
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• 1996

Orthodontic patients are individuals that grow and develop ; therefore selection of the proper time for orthodontic treatment is considered to be one of most difficult and yet difficult factor. Since the development of cephalometric X-ray, amount and Pattern of craniofacial growth change with aging could be predicted and be came useful in the process of orthodontic treatment. The relationship between the mean values of cephalometric measurements and body height and weight was studied among the groups(boys and girls) of Korean children from the ages 6-years to 17-years. 409 boys and 437 girls with no abnormality in growth and development and no history of orthodontic treatment from the ages of 6 years to 17 years were chosen as subjects Cephaloment X-ray were taken for 3 years and hard tissue analysis based on Burstone's COGS, which was devided into measurements of 6 parts(Cranial base, Maxillar and Mandible, Dental measurements). The relationship between craniofacial growth and height & weight was studied. The following conclusions were obtained : 1. The maximum growth in the measurements of cranial base, N-Ar(FH), N-Ba(FH) corresponded with the age with the maximum increase in body height & weight in both boys and girls. 2. Genial angle gradually decreased with aging in both boys and girls. 3. N-ANS(L) showed greater amount of growth than ANS-Ne(L), and this had greater influence on facial profile. 4. N-A-$Pog^{\circ}$ decreased with aging, and mandibular growth exceeded maxillary growth in amount and rate. 5. Length of Y-axis Increased, but Y-axis to FH plane remained constant. This show that mandible grows at a constant angulation to cranial base. 6. As permanent teeth erupt, interincisal angle deceased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.18
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• pp.124-155
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• 1975

To obtain the fundamental informations on the varietal improvement of peanut and to study the ecological variations of the important agronomic traits and to the relationship between the traits studied, an investigation was made on varietal classification of 489 introduced on the basis of their morphological and ecological differences at Crop Experiment Station, Suweon in 1968, and the other study conducted at some location as above in 1969 was to investigate the ecological variations of the materials in accordance with changes of seeding date using classified varietal group under 5 different seeding times from April 16 to July 7 with twenty days interval. The results obtained were summarized as follows: 1. Peanut varieties tested were classified into Spanish, Virginia Erect, Virginia Runner, Southeast Runner. Valencia and Semirunner, on the basis of plant type, flowering time, number of grains per pod and grain size. 2. Characteristics of varietal group classified are as followings. (1) Spanish; erect, small grained and early maturing type. (2) Virginia Erect; erect, large grained and late flowering type. (3) Virginia Runner; runner, large grained and late maturing type. (4) Southeast Runner; runner, small grained and early maturing type. (5) Valencia; erect, small grained and early flowering type with 3-4 grains per pod. (6) Semi runner; semirunner, large grained and late flowering type. 3. Flowering period in respective varietal group was consistently shorted by delayed seeding date and the degree of shortening was more serious in late flowering varietal group. 4. Number of branches per plant was generally decreased in late seeding date in respective group. However, Spanish and Virginia Runner exhibited lower number of branches in the first seeding rather than the second seeding and the lowest number of branches was found in Spanish while the highest were Virginia Erect in all seeding date. 5. Shelling ratio was high in Spanish and Southeast Runner in any seeding date and decreased remarkedly by seeding after May. 6. Number of pod per plant in all varietal groups was remarkedly decreased by delayed seeding date and the degree of decreasing was more serious in large grain varietal group. 7. The higher pod weight per plant was found in second seeding date rather than first seeding and pod weight per plant was decreased obviously in all late seeding after the second. Therefore, among the cultivars tested, Southeast Runner noted the highest pod weight per plant while Virginia Runner showed the lowest. 8. Grain number per plant expressed the similar tendency as the pod weight per plant but was low in large grain group and high in small grain group in all seeding date employed. 9. 100 grain weight was heaviest in second seeding and was decreased remarkedly after the second and even the first seeding date. 10. Yield per 10a noted considerable variations in accordance with seeding date in all groups classified. However, the yield was increased in second seeding date (May 7) and decreased in the others. 11. Length of main stem and branches were exceptionally decreased in the first seeding date compare to the second in Spanish while other varieties were tend to be same between the indicated seeding date, but. these two traits were strikingly decreased in all seeding after the second. This tendency, however, strongly suggested the importance of environmental effects on peanut growth in terms of their changes due to the different seeding date. 12. Highly significant positive correlations were showed between yield and yield componets such as pod weight per plant, 100 grain weight and the number of grains per plant in all varietal groups except, Virginia Runner. However, the other characters were almost not correlated with yield and differences in correlation coefficients among the seeding dates were found. 13. Path coefficients estimated for yield components to yield was higher in number of grains per plant pod weight per plant and 100 grain weight in terms of direct effect and the other components were negligible in all varietal groups. 14. Heritabilities estimated were generally high in pod number per plant, shelling ratio, 100 grain weights and number of grains per pod and the other traits were relatively low.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.9 no.1
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• pp.1-18
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• 1973

For regulating the depth of midwater trawl nets towed at the optimum constant speed, the changes in the shape of warps caused by adding a weight on an arbitrary point of the warp of catenary shape is studied. The shape of a warp may be approximated by a catenary. The resultant inferences under this assumption were experimented. Accordingly feasibilities for the application of the result of this study to the midwater trawl nets were also discussed. A series of experiments for basic midwater trawl gear models in water tank and a couple of experiments of a commercial scale gears at sea which involve the properly designed depth control devices having a variable attitude horizontal wing were carried out. The results are summarized as follows: 1. According to the dimension analysis the depth y of a midwater trawl net is introduced by $$y=kLf(\frac{W_r}{R_r},\;\frac{W_o}{R_o},\;\frac{W_n}{R_n})$$) where k is a constant, L the warp length, f the function, and $W_r,\;W_o$ and $W_n$ the apparent weights of warp, otter board and the net, respectively, 2. When a boat is towing a body of apparent weight $W_n$ and its drag $D_n$ by means of a warp whose length L and apparent weight $W_r$ per unit length, the depth y of the body is given by the following equation, provided that the shape of a warp is a catenary and drag of the warp is neglected in comparison with the drag of the body: $$y=\frac{1}{W_r}\{\sqrt{{D_n^2}+{(W_n+W_rL)^2}}-\sqrt{{D_n^2+W_n}^2\}$$ 3. The changes ${\Delta}y$ of the depth of the midwater trawl net caused by changing the warp length or adding a weight ${\Delta}W_n$_n to the net, are given by the following equations: $${\Delta}y{\approx}\frac{W_n+W_{r}L}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}{\Delta}L$$ $${\Delta}y{\approx}\frac{1}{W_r}\{\frac{W_n+W_rL}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}-{\frac{W_n}{\sqrt{D_n^2+W_n^2}}\}{\Delta}W_n$$ 4. A change ${\Delta}y$ of the depth of the midwater trawl net by adding a weight $W_s$ to an arbitrary point of the warp takes an equation of the form $${\Delta}y=\frac{1}{W_r}\{(T_{ur}'-T_{ur})-T_u'-T_u)\}$$ Where $$T_{ur}^l=\sqrt{T_u^2+(W_s+W_{r}L)^2+2T_u(W_s+W_{r}L)sin{\theta}_u$$ $$T_{ur}=\sqrt{T_u^2+(W_{r}L)^2+2T_uW_{r}L\;sin{\theta}_u$$ $$T_{u}^l=\sqrt{T_u^2+W_s^2+2T_uW_{s}\;sin{\theta}_u$$ and $T_u$ represents the tension at the point on the warp, ${\theta}_u$ the angle between the direction of $T_u$ and horizontal axis, $T_u^2$ the tension at that point when a weights $W_s$ adds to the point where $T_u$ is acted on. 5. If otter boards were constructed lighter and adequate weights were added at their bottom to stabilize them, even they were the same shapes as those of bottom trawls, they were definitely applicable to the midwater trawl gears as the result of the experiments. 6. As the results of water tank tests the relationship between net height of H cm velocity of v m/sec, and that between hydrodynamic resistance of R kg and the velocity of a model net as shown in figure 6 are respectively given by $$H=8+\frac{10}{0.4+v}$$ $$R=3+9v^2$$ 7. It was found that the cross-wing type depth control devices were more stable in operation than that of the H-wing type as the results of the experiments at sea. 8. The hydrodynamic resistance of the net gear in midwater trawling is so large, and regarded as nearly the drag, that sweeping depth of the gear was very stable in spite of types of the depth control devices. 9. An area of the horizontal wing of the H-wing type depth control device was $1.2{\times}2.4m^2$. A midwater trawl net of 2 ton hydrodynamic resistance was connected to the devices and towed with the velocity of 2.3 kts. Under these conditions the depth change of about 20m of the trawl net was obtained by controlling an angle or attack of $30^{\circ}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.2
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• pp.281-313
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• 1976

To obtain fundamental informations on cotton breeding efficiences for Korea, individual genetic relationships and interrelationships between the agronomic characteristics of Upland cotton were investigated. These experiments were couducted at the Mokpo Branch Station $(34^{\circ}48'N, $ $126^{\circ}23'E$ and altitude of 10m above sea level) from 1969 through 1972. Heterosis, combining ability, dominance and recessive gene action, genetic variance, and phenotypic and genotypic correlation were investigated by $F_1'S$ from an 11-parent partial diallel cross and the segregating $F_2$ and $F_3$ populations of the cross Paymaster times Heujueusseo Trice. The following points resulted from this study, 1. Heteroses for number of bolls per plant and lint yield were significant at 27, 84% and 37.26%, respectively. No other character had significant heteroses. 2. The GCA estimates for all studied characteristics were higher than the SCA estimates. Varieties with high GCA effects were Suwon 1 for earliness, Paymaster and Arijona for high lint percent, and Arijona for long fiber, etc, 3. SCA estimates for lint yield varied widely in crosses with Mokpo 4, Mokpo 6 and Heujueusseo Trice. Those crosses with the highest SCA effects were combinations with large characteristics differences, Example of these crosses are Mokpo 4 times Acala 1517W, Mokpo 4 times D. P. L. and Heujueusseo Trice aud Paymaster. 4. Early-maturing varieties were completely dominant to late-maturing varieties in some combinations while other crosses gave intermediate phenotypes. These results suggest additive genetic action by multi-genes. Heujueusseo Trice, Mokpo 6, and Suwon 1 showed highest degree of dominance for earliness. 5. There were no significant trends for inheritance of weight of boll and 100 seeds weight. 6. Long staple was partially to completely dominant to short staple. Though there were single gene ratios the rate of dominance decreased in the $F_2$ and $F_3$ populations in the cross between the long staple variety Paymaster and the short staple variety Heujueusseo Trice. Diallel cross $F_1$ hybrids showed complicated allelic gene action for staple length. Various dominance degree were shown by varieties. 7. Number of bolls per plant indicated strong over-dominance and small non-allelic additive gene action. 8. Lint Yield was characterized by over-dominance and by multiple non-allelic-gene action. High-yielding varieties were dominant to low-yielding ones. However, the low-yielding variety Heujueusseo Trice showed over-dominance, indicating different reactions according to the varieties and combinations. 9. Broad sense heritability for days to flowering was 34-39% while narrow sense heritability was 11%. Large variations of individual plants caused by Korean climatic conditions cause this situation. Heritability estimates for weight of boll was 30% for broad sense and 22% for narrow sense. 10. Heritability estimates for staple length and lint percent were very high suggesting strong selection effects. 11. Narrow sense heritability estimates for number of bolls per plant was 30% in the diallel cross $F_1$ hybrids and 36% in the $F_2$ population of the special cross. Broad sense heritability was estimated at 67% suggesting that. 12. Heritability estimates for lint yield was low due to high over-dominance in the diallel cross $F_1$ hybrids. Heritability estimates for yield was low in the $F_1$ hybrids but high in the $F_2$ and $F_3$ populations. 13. Phenotypic and genotypic correlations between lint percent and days to flowering and between staple length and days to flowering were high in the $F_1, $ $F_2$ and $F_3$ populations. Late-maturing varieties and individuals had long staple and high lint percent in general. As the correlation between days to flowering and lint yield was extremely low, the two traits were considered independent of each other. Days to flowering and number of bolls per plant were negatively correlated in the $F_3$ population, indicating early-maturing individual plants with many bolls may be readily selected. 14. Phenotypic and genotypic correlations between lint percent and staple length were high in $F_1, $ $F_2$ and $F_3$ populations. Accordingly, long staple varieties were high in lint percent. It was recognized that lint yield and lint percent were positively correlated in the diallel cross $F_1$ hybrids, and lint percent and staple length were positively correlated in the $F_2$ population, indicating that lint percent and staple length affect lint yield. 15. Lint yield was significantly and positively phenotypically correlated with number of bolls per plant in $F_1, $ $F_2$ and $F_3$ populations. A high genotypic correlation was also noted indicating a close genetic relationship. The selection efficiencies for a high-yielding variety can be increased when individual plants with many bolls are selected in later generations. The selection efficiencies for good fiber quality can be enhanced when individuals with long staple and high lint percent are selected in early generations.

• Journal of Aquaculture
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• v.7 no.4
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• pp.189-205
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• 1994

Formerly, adult-tiger puffer, Takifugu rubripes with ova caught in the sea, were used for seedling production. But it was difficult to secure naturally-ripened adults. For the purpose of adult tiger puffer in captivity, this study was carried out. To determine the growth 220 tiger puffers hatched in 1990 (3-year-old) and 1991 (2-year-old) were used. For spawning and egg incubation leading to fry development, eggs were stripped from tiger puffers hatched in 1988 (5-year-old) and 1990 (3-year-old) through human chorionic gonadotropin (BCG) treatments. In May, 1993, mean body length and mean body weight of 2-year-old tiger puffer were $30.72\pm1.35cm\;and\;1,048\pm228 g,$ and that of 3-year-old tiger puffers were $36.02\pm1.17cm$ and $1,402\pm66g$ respectively. The relationship between body length (L) and body weight (W) of 2-year-old the tiger puffers during the experiment period was represented as $W\;=\;1.7892L^{31524}\times10^5$ (r= 0.9436) and that of 3-year-old, $W=\;3.2840L^{36099}\times10^6$ (r= 0.9070) respectively. The GSI in female 2-year-old-fish changed from $0.23\times0.l2\;to\;0.74\pm0.08$, during the experiment period, and in male it didn't change remarkably until November, but thereafter it increased and showed a peak of $8.69\pm5.09$. The GSI of 3-year-old-fish showed a peak of $8.05\pm5.58$ in April in female and $12.65\pm4.60$ in May in male. The change of HSI in 3-year-old-fish was correlative to the change of GSI, but in 2-year-old-fish it was little correlative. In female gonad of 2-year-old tiger puffer, the mature oocytes reached $350{\mu}m$ in April, but thereafter they didn't spawn and became atrophied. But in male gonad, a great number of spermatozoa were crowded in the testicular lobuli in April. Female gonad of 3-year-old tiger puffer had the mature oocytes of 650 pm in March and the ripe oocytes, $900{\mu}m$ in April. Male testis development was similar to that of 2-year-old-fish. Egg-stripping after hormone treatments was possible past 139 hours and 142 hours from each of two 5-year-old-fish (500IU/kg, BW), and after 114 hour from a 3-year-old-fish (1,000 IU/kg, BW) under water temperature $16.3\~17.8^{\circ}C$. Eggs stripped amounted was 650 g and 400 g from two 5-year-old-fish and 610 g from the 3-year-old-fish, and fertilization rates were $98.0\%,\;97.4\%\;and\;96.5\%$ respectively. All the hatched larvae devloped into normal fry.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.2
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• pp.30-37
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• 1964

Experiments were carried out to clarify the relationships between seed yields and some ecological characteristics, seed yields and some morphological characteristics, and the relationships among the varietal yields on the several sowing plots when grown under different climatic conditions. Twenty-four soybean varieties were used as the material, selected at random from 138 varieties which were cultivated the year before. These varieties were grown in the Experimental Farm, Chinju Agricultural College, Kyung Sang Namdo, Korea, and seed sowing was conducted at 5 times, from April to July, in 1962 and 1963. The results obtained are summarized as follows: 1. Correlations between seed yields and some ecological characteristics on the sowing date bases are shown in Table 1. Among some ecological characteristics, it was observed that there wert close relationships between seed yields and days to flowering, and between seed yields and the total growing length, except on the late sowing, i.e. July sowing plots, However, there was no clear correlation between seed yields and durations of flowering, and between seed yields and days from flowering to maturity. 2. Correlations between seed yields and some morphological characteristics on the sowing date bases are shown in Table 2. From this table, it was also observed that there were some close relationships between seed yields and branch number for plant, stem diameter, plant weight, pod number per plant, and grain number per plant, but there was no clear relationship between seed yields and stem length, and between seed yields and 100 grain weight, on every sowing plot. 3. Relations between varietal yields and the sowing dates are shown in Table 3. Our leading varieties such as Ulsan, Sangdoo, Changdan Backmok, Iksan, Haman, Barchongdeo, and Anion Daerip, which belong to the maturity groups of IV, V, and VI, have been significantly high in yield at each sowing date plot, but the extreme early varieties, that frequently are damaged by insects, moisture and diseases, and the extreme late varieties, that frequently are caught by frost suffering reduced yield, are showed a lower yield than the others. However, extreme early varieties, for instance, Black Hawk, an American variety, and Chung Buk Baek, a Korean early variety, showed high productivity on the late sowing, June and July sowing plots, and Do san No. 6, which is late Japanese variety, showed a high yield on the extreme early sowing, i.e. April sowing plots. 4. Relations between seed yields and the sowing dates on the varietal bases are shown in Table 4. It was observed that, the early varieties did not differ much in yields at the various sowing dates while the yields of late varieties decreased progressively with subsequent dates. However, the extreme late varieties, such as Tamanishiki, that frequently are caught by frost suffering reduced yield, may be difficult to harvest at this location. The results in these experiments showed that in most cases maximum yields were obtained when leading varieties, which are medium or late varieties, were shown in Mid-May, and progressively lower yields were produced from June and July sowings. On the other hand, the late sowings of the early varieties, such as Black Hawk and Chung Buk Baek, in these experiments showed favorable yields compared with the others. From these results, we can predict that our local medium or late varieties produce higher yields at this location than was produced by early varieties in most of the sowing dates, especially the May sowing, and early varieties such as Black Hawk and Chung Buk Baek should be used in the late sowing, June sowing time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.2
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• pp.27-29
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• 1964

Experiments were carried out to clarify the relationships between seed yields and some ecological characteristics, seed yields and some morphological characteristics, and the relationships among the varietal yields on the several sowing plots when grown under different climatic conditions. Twenty-four soybean varieties were used as the material, selected at random from 138 varieties which were cultivated the year before. These varieties were grown in the Experimental Farm, Chinju Agricultural College, Kyung Sang Namdo, Korea, and seed sowing was conducted at 5 times, from April to July, in 1962 and 1963. The results obtained are summarized as follows: 1. Correlations between seed yields and some ecological characteristics on the sowing date bases are shown in Table 1. Among some ecological characteristics, it was observed that there wert close relationships between seed yields and days to flowering, and between seed yields and the total growing length, except on the late sowing, i.e. July sowing plots, However, there was no clear correlation between seed yields and durations of flowering, and between seed yields and days from flowering to maturity. 2. Correlations between seed yields and some morphological characteristics on the sowing date bases are shown in Table 2. From this table, it was also observed that there were some close relationships between seed yields and branch number for plant, stem diameter, plant weight, pod number per plant, and grain number per plant, but there was no clear relationship between seed yields and stem length, and between seed yields and 100 grain weight, on every sowing plot. 3. Relations between varietal yields and the sowing dates are shown in Table 3. Our leading varieties such as Ulsan, Sangdoo, Changdan Backmok, Iksan, Haman, Barchongdeo, and Anion Daerip, which belong to the maturity groups of IV, V, and VI, have been significantly high in yield at each sowing date plot, but the extreme early varieties, that frequently are damaged by insects, moisture and diseases, and the extreme late varieties, that frequently are caught by frost suffering reduced yield, are showed a lower yield than the others. However, extreme early varieties, for instance, Black Hawk, an American variety, and Chung Buk Baek, a Korean early variety, showed high productivity on the late sowing, June and July sowing plots, and Do san No. 6, which is late Japanese variety, showed a high yield on the extreme early sowing, i.e. April sowing plots. 4. Relations between seed yields and the sowing dates on the varietal bases are shown in Table 4. It was observed that, the early varieties did not differ much in yields at the various sowing dates while the yields of late varieties decreased progressively with subsequent dates. However, the extreme late varieties, such as Tamanishiki, that frequently are caught by frost suffering reduced yield, may be difficult to harvest at this location. The results in these experiments showed that in most cases maximum yields were obtained when leading varieties, which are medium or late varieties, were shown in Mid-May, and progressively lower yields were produced from June and July sowings. On the other hand, the late sowings of the early varieties, such as Black Hawk and Chung Buk Baek, in these experiments showed favorable yields compared with the others. From these results, we can predict that our local medium or late varieties produce higher yields at this location than was produced by early varieties in most of the sowing dates, especially the May sowing, and early varieties such as Black Hawk and Chung Buk Baek should be used in the late sowing, June sowing time.